Telephone system.



J. C. Fl. PALMER.

TELEPHONE SYSTEM.

APPLICATION FILED MAY10,19I3.

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snares manner JOEL C. R. PALMER, OF NEW ROCHELLE, NEW YDRK, ASSIGNOR TO WESTERN E1133 COMPANY, OF NEW YORK, N. Y., A GORPOBIATION OF ILLINQIEL TELEPHONE srsrnivr.

Specification of Letters Batcnt.

Application filed May 10, 1913. Serial Ztl'o. ?66,863.

To all whom it may concern."

Be it known that l, rlone C. R. "Banner, a citizen of the United States, residing at New Rochelle, in the county of lVestchester and State of New York, have invented a certain new and useiu]. improvement in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to a common battery telephone system and more particularly to a transmission. system for comparatively long lines with which are associated a plurality of substations.

The object of this invention is to provide a novel and improved combination of substation circuit apparatus whereby a plurality of substations on the same line may be efficiently operated from a common battery source.

This invention is particularly adapted for use with systems having a plurality of substations on a single telephon line, such for instance, as train despatching or fire control systems, said substations being arranged to be brought into circuit simultaneously with the oliice of the central operator or des patcher for the purpose of receiving a general order. Heretofore, this has been impracticable in common battery telephone systems, due to the division of the available current between the various stations which limits the current for each transmitter to a quantity less than is desirable for good transmission.

This feature may be overcome by cutting out the flow of current through a substation, except when its transmitter is in actual use, and the invention resides in providing a closed path for telephonic current in bridge of the telephone line, said bridge containing a receiver and means for preventing the flow of direct current through said bridge, and additional means for including a transmitter in said bridge.

In the embodiment of this invention in a telephone set, switching means is provided at each substation normally completing the receiving circuit in bridge of the line through a condenser, and is arranged when opera ed to connect a transmitter in said 5 and 6.

bridge and to include a in shunt of the receiver.

In the accompanying drawings, F n irepresents a substation. circuit in wine invention is embodied; Fig. 2 shows the cult and apparatus which is bridged a the telephone linewhen the receiver is on the switch hook; Fig. 3 shows the receiving circuit when the receiver is removed on the switch hook; and Fig. i shows the i. rangement of the receiving and transmitter circuits when the switching means is operated.

Beferringto the drawings, and particu larly to Fig. l, and 6 designate the line wires forming the telephone line, which unites the various substations (only one shown) with the central oiiice (not shown). At each substation is located ringer 10 and a condenser 11 in'scries therewith, which are at all times bridged acrossthe line wires At each station is a high impedance receiver 12 having in series there-- with a condenser 13, the receiver and condenser being adapted to be placed in bridge oi the line wires 5 and 6 by the operation ofthe receiver switch hook 1 which. closes switch hook contact 15, said brid including a normally closed contact ll switch key 18. 7 Operation of the a rich hook 1 14 also closes contact 20, which places a shunt around the condenser 11, to form path for direct current between the line wires.

A secondary 25 of an induction coil 26 is bridged directly across the line wires 5 and (3 in series with a non-inductive tapering re sistance 27' and a transmitter 28 by the closure of the normally open contacts 16, 29 and 30, 31., 82 of the switch key 18. The taparing resistance 27 is non-inductive and the value thereof differs for each station, the purpose of the resistance being'to compensate for line resistance between stations so that each station will receive the same amount of current. By the closure of contacts 30, 31, 32 of the switch key 18, the receiver 12 and condenser 13 are bridged around the transmitter 28 in series with a primary 33 oithe induction il 26, and a Bil the receiver 12.

Assuming now that an operator at the substation is listening and receiving a message, switch key 18 remains in the position shown and the path for the incoming voice currents includes the receiver 12 and the con denser 13 in bridge directly across the. line wires 5 and 6, as shown in Fig. 3. When the operator at the substation desires to talk over the line, he actuates switch key 18,

opening contacts 16, 1'7 and closing contacts 16, 29 and 30, 31, 32. The opening of the contacts 16, 17 disconnects the receiver 12 and condenser 13 from the line wires 5 and 6. Closing the contacts 16, 29'and 30, 31, 32 bridges the transmitter 28 directly across the telephone line in series with induction coil secondary 25 and tapering resistance 27, and associates therewith for the outgoing voice currents at local amplifying circuit including induction coil primary 33, condenser 13, low impedance path 34 and transmitter 28. At the same time a changed path is provided for the incoming voice currents including the induction coil primary 33, condenser 13 and receiver 12. The amplifying circuit through the inductive action of the condenser 13 amplifies the undulations set up by the transmitter 28. A detailed description of such an amplifying circuit is to be found in Patent 669,710 of March 12, 1901 to C. E. Scribner.

WhatIclaim is: a

1..In a telephone transmission circuit, a n

means for closing said transmitter c1rcu1t telephone line, a normally open high impedance receiving circuit connected with said telephone line, a switch for closing said receiving circuit, a normally open transmitter circuit, and switching means for closing said transmitter c1rcu1t and simultaneously connectlng said receiving c1rcu1t 1n shunt of said transmitter circuit.

2. In a telephone transmission circuit, a telephone line, a condenser, a normally open high impedance receiving circuit connected with said telephone line through said con.- denser, a switch for closing said. receiving circuit, a normally open transmitter circuit,

'and switching means for closing said transmitter c1rcu1t and simultaneously connecting said condenser and said high impedance receiving circuit in shunt of the transmitter.

3. In a telephone transmission circuit, a telephone line, an induction coil having two windings, a normally open high impedance receiving circuit connected with said telephone line, a switch for closing said receiving circuit, a normally open transmitter circuit including one winding of said induction coil, and switching means for simultaneously closing said transmitter circuit and connecting said high impedance receiving circuit in shunt of said transmitter circuit.

4. In a telephone transmission circuit, a telephone line, an induction coil having two windings, a condenser, a normally open high.

windings, a normally open high impedance receiving circuit connected with said telephone line, a switch for closing said receiving circuit, a normally open transmitter cir cuit including one winding of said induc' tion coil, and switching means for closing said transmitter circuit and simultaneously reducing the impedanceof the receiver circuit andconnecting it in shunt of said transmitter circuit.

6. In a telephone transmission circuit, a telephone line, an induction coil having two windings, a normally open high impedance receiving circuit connected with said telephone line, a switch for closing said receiving circuit, a normally open transmitter circuit including one winding of said induction coil, a normally open local amplifying circuit for said transmitter circuit including Hsaid induction coil primary, a condenser and a, nominductive resistance, and switching and said local amplifying circuit.

7. In a telephone transmission circuit, a telephone line, an induction coil having two windings, a condenser, a high impedance re ceiving circuit connected with said telephone line through said condenser, a normally open transmitter circuit including one winding of said induction coil, anormally open local energy-amplifying circuit for said transmitter circuit including the otherwinding of said induction coil, a low impedance path, and switching means for simultaneously including said condenser andsaid low impedance path in said local energy-amplifying circuit, closing said transmitter circuit and connecting said local energy-amplifying circuit in shunt of said transmitter circuit.

8. In a telephone transmission circuit, a telephone line. an induction coil having two windings, a condenser, a normally open high impedance receiving circuit connected with said telephone line through said condenser, a switch for closing said receiving circuit,

a normally open transmitter circuit includmamas ceivin' circuit, connecting said condenser and said low impedance path in said local amplifying circuit, closing said transmitter circuit, inductively associating therewith 5 said receiving circuit, and connecting said local amplifying circuit in shunt of said transmitter circuit.

In witness whereof, I hereunto subscribe my name this 7th day of May A. 1)., 1913.

J OEL 01R. PALMER.

Witnesses:

W. F. HOFFMAN, W. H BROWN. 

